What do you think?

[xxxleafybugxxx]

Those of you who know more about scopes/mounts will be able to answer this question better than I can.
I've had some Federal .308's laying around in my dresser for some time, so I rounded them up and used them in my scoped M1a yesterday.
I had shot a 4 shot group with the Federal Power Shok ammo (which my M1a absolutely loves). 3 of the 4 shots were grouped within 1 inch, while the other was about 1.5 inches low. this is where the question comes...
My first thought is that the low shot was a 180 grain bullet, and the other 3 were 150 grain, or could it be the scope/mount is moving? I would hope to assume the other shot was a different round, but I'm here to get your opnion. I won't know for sure until I get more ammo and take it out again. If the scope/mount was moving, would 3/4 shots within an inch be likely?
Thoughts?

 

[fireman 9731]

Different weight bullets will shoot to a different point of aim depending on how your scope is sighted in. What distances were you shooting at?

And one and a half inches low isn't alarming to me, if you shot 4 others within an inch. The 5th one is simply a flyer. could of been the guns fault, could of been the rounds fault, could of been your fault. This is why 3 shot groups are usually better than 5 shot groups.

 

[xxxleafybugxxx]

I was shooting from 100 yards

 

[fireman 9731]

I would call it a flyer and wait to shoot a few more rounds before I worried any.

 

[gamestalker]

Different bullet weights, different manufacturer / designs and lot numbers equate to expected variance in where they print. Also barrel whip is going to be significantly different between those weights as well. Anbd how much time between shots will make some difference also.

There are other mitigating factors that have an impact as well, and some of those involve the operator.
GS

 

[red-demon652]

Agree

 

[cougar1717]

With factory ammo (even the kind your rifle likes), four shots is very inconclusive. If it continues to be repeatable, that may be cause for some sort of concern. Having a flyer, even with handloads can be quite common.

 

[CountryUgly]

You didn't follow the sniper's first rule of jerking the trigger between heart beats. Gees rookie shooters always do this. Now you need to go home and practice dry firing for hours on end to get your breathing and timing in the same rythme as your heart beat. There should of been only one hole if you fired four shorts . Your marksmanship is unacceptable.
Sorry I had to toss a Mall Ninja answer in there.

Seriously it was probably just a flyer don't sweat it.

 

[TonyAngel]

First, there's no such thing as a "flyer," in the sense that a round landed outside of the typical group for no reason. If a round lands outside of what a rifle is typically capable of shooting, it did so because something went wrong.

Since the OP was able to put three rounds within an inch, it is an indicator that the OP has some skill and that the rifle is capable of MOA accuracy. It isn't definitive, but is an indicator. That one round landing outside of the group, in this case, seems to have been caused by the fact that it was a different weight bullet.

Many things will cause different loads to have a different point of impact. The weight of the bullet, the powder type used, the shape of the bullet, etc. In this case, a 1.5" deviation isn't out of the ordinary.

For example, if you consider this series of groups. Note that the only difference among the loads is .5gr of powder. Same brass, bullets and powder.


The 42gr load had a tendency to put the point of impact a little high. The 42.5gr load was right on target and the 43gr load looks like it would be a little low. For reference, the diamond is 3/4" (or was it 1", I don't remember) from the top tip to the bottom tip. The groups were shot at 100 yards.

The point being that it doesn't take much to shift a point of impact.

On another note, this rifle is capable of putting all of the rounds through the same hole. I've done it on MANY occasions using a front and rear rest, bench rest style. In many of the groups above, two rounds went into about the same hole and the third went out. Am I to call these flyers? I'd say no. They went exactly where I put them, although putting them there was my screw up. Probably an inconsistency in form.

Now, I don't know what posts like this are about...

You didn't follow the sniper's first rule of jerking the trigger between heart beats. Gees rookie shooters always do this. Now you need to go home and practice dry firing for hours on end to get your breathing and timing in the same rythme as your heart beat. There should of been only one hole if you fired four shorts . Your marksmanship is unacceptable.
Sorry I had to toss a Mall Ninja answer in there.

I find this offensive to those that make the effort and take to time to become more proficient at what they like to do.

 

[ladytech777]

If I shot that well -I'd stop practicing! LOL!

 

[TonyAngel]

Thanks, but gotta keep practicing. Use it or lose it.

 

[Yarddog]

Eyes Get old, Then need better scope
Y/D

 

[TonyAngel]

Eyes Get old, Then need better scope

Yeah, I'm starting to wonder how much it would cost to rent the Hubble Telescope. I need to find a mount first, though.

 

[BullfrogKen]

I would say you cannot make any conclusions from what you did.

You shot four rounds. Three that were the same. And one that was not like the others.


Anyone remember that Sesame Street song?

One of these things is not like the other.
One of these things just doesn't belong.
One of these things is not like the other.
Guess which one.
​

And that's what you've left yourself.

Guessing.


Go buy a full box of ammo that is all the same, and shoot a few 5 round groups. I don't use 3 shot groups for anything I'm trying to test. When I shoot hand loaded rounds over a chrony I do ten shot tests. Same with my handload development rounds to test powder charges for a given bullet weight.

With 3 and 5 round groups I start to second guess my batch, or second guess myself. I round up to 10, and 10 is enough to see "flyers" I pulled as a result of my error as a shooter that I can toss out and still have enough left to make an informed decision on.

 

[TonyAngel]

I would say you cannot make any conclusions from what you did.

Well, what I did was dig up an old test target that I had because I was trying to illustrate the difference that minute changes in variables can make to points of impact. I think that the target that I posted does show minute changes in points of impact, although using the target for this purpose does sort of have you looking for trends. The trends are none the less, there.

As for what I was trying to do, you assume a lot. You criticize my use of three shot groups; but those are not three shot groups. Those are 9 shot groups shot over three targets. MY purpose for shooting those was to aid in my hunt for a synergy among the rifle, ammo and shooter.

Groups mean nothing to me if I can't hit my target, transition to a new target and know where the bullet is going to hit, so for my purposes, those targets show me exactly what I want to know. I'm not testing to see if my rifle can accurately shoot ten shot groups at a single target. I already know it can.

I also shot these on the same weekend...












Based on what I learned using this method, I still shoot 175s for longer ranges using charges of 42.5gr of RL15 for 600 yards and 44gr of RL15 for longer distances because they help me to maintain the most consistency with that rifle.

For me it's about taking variables and turning them into constants. I know that this may seem unorthodox, but shooting from a bipod takes a bit of a knack and it really helps to get everything working together in the manner in which I need them to work together.

 

[d2wing]

Not enough info to conclude anything. If you'd shot 3 of each we'd have a better idea. Tony and Bullfrog are both right. It's hard to predict what small changes do to poi. We could conclude that poi is different for the 180 gr, but it could be another factor.

 

[SabbathWolf]

I only judge the best accuracy I can achieve from cold bore shots.
I don't own an M1a nor have ever fired one.
So, I don't know how long or little they take for the barrel to warm up.
How long did you wait between each shot?

The reason I ask is because I've seen "some" rifles that will change in POI in as little as 5 rounds if shot fairly rapidly.
Sounds nutz, but it's true.
Just a passing thought.......

 

[TonyAngel]

Not enough info to conclude anything.

How much info do you need to conclude that a load is going to do what you want it to do? I don't need to shoot 20, 10 round groups to get a good idea of what this rifle is going to do with a particular load.

I mean, geez...all of the groups shot were very sub MOA. It can be hard to see differences at that point, but if you don't see them, I apologize for having posted anything.

At the point I have to add and edit of the posted target sheets. I went back and checked my records and the last three sheets were shot with a different rifle. It was and SPS Tactical.

SabbathWolf, the rifle that shot the groups in the first post and the first three sets of targets in the second post has a Krieger heavy varmint barrel. This particular barrel has been very good to me. The first cold bore shot goes to the same POI as the following shots. I don't do any sort of cooling off period. I just shoot when I'm ready to. Once I do start shooting, I shoot as fast as I can get back on target. I do most of my shooting from a prone position, so I don't spend too much time just lying around on the ground.

 

[SabbathWolf]

SabbathWolf, the rifle that shot the groups in the first post and the first three sets of targets in the second post has a Krieger heavy varmint barrel. This particular barrel has been very good to me. The first cold bore shot goes to the same POI as the following shots. I don't do any sort of cooling off period. I just shoot when I'm ready to. Once I do start shooting, I shoot as fast as I can get back on target. I do most of my shooting from a prone position, so I don't spend too much time just lying around on the ground.

OK then.
I'm just trying to rule out the rifle -vs- the ammo.